The present invention relates to a positioning device, in particular a tool positioning device, for a processing center, in particular a horizontal processing center, and a processing center with such a positioning device.
Machine tools, for example, for subjecting workpieces having various configurations to a chip removing process, ranging from small table machines to large processing centers for processing large parts have been known. In particular when large parts are being processed, for example in tool, mold and model making, or during production in the automobile and aerospace industries and in comparable applications, it is necessary to produce complex surfaces displaying the highest surface quality on large workpieces and at high processing rates. To do so, usually high-precision guides are used, in particular linear guides, on which slides can be moved in various directions for precisely positioning a workpiece and/or a processing unit, e.g., a milling head, in the processing space. In general, the guides comprise guide elements provided on the slide such as, for example, guide shoes or rail runner elements that are guided on the guide rails supported by rolling bodies. The slides may be associated with linear drives in order to be able to move them in a motor-driven manner.
Horizontal processing machines or centers, wherein a processing spindle, e.g., a milling spindle, held in a horizontal position on a carrier, can be moved in a work space and fixed in position in any pivot position, while a workpiece, e.g., on a workpiece palette is loaded in a horizontal position and transferred into a vertical processing position, have been known. For maximum flexibility, the processing spindle can be guided and positioned in a first horizontal direction, in particular the longitudinal direction of a processing machine or a processing center, a second horizontal direction, in particular a transverse direction for a delivery and resetting movement of the processing spindle relative to the workpiece, and be movably guided and positioned in a first vertical direction. In doing so, maintaining the greatest possible flexibility with respect to positioning in a large processing space and the simultaneous, simple, compact and cost-effective construction of the machine or the processing center should provide a guide that is stiff, stable and precise.
From EP 2 666 566 B1 there is known a turning machine that comprises a workpiece spindle unit that is movably arranged on a machine bed. The tool spindle unit comprises a longitudinal slide that can be moved in longitudinal direction on the machine bed in linear guides. On the longitudinal slide, there is provided a cross slide such that it can be guided in transverse guides. On the cross slide, there is provided a vertical slide such that it can be moved in vertical guides. In particular, the machine bed has an offset configuration, wherein a first and a second guide rail of the longitudinal guides are arranged parallel to each other at different heights or horizontal planes of the machine bed. As a result of this, a constant, enlarged guiding distance between the longitudinal guide rails can be maintained with a reduced footprint of the machine bed. The longitudinal slide, in turn, carries on its upper side two parallel guide rails that extend on a common horizontal plane in transverse direction in order to guide the cross slide. The cross slide, in turn, comprises the vertical guides for the vertical slide. The vertical slide supports the spindle unit for processing a workpiece that thus can be freely positioned within a limited region of the work space in the vertical directions relative to each other.
Similar machine tools have also been known from DE 102 59 215 A1 and DE 100 58 627 A1.
Considering this, it is an object of the present invention to provide a positioning device for a workpiece or a tool, and a processing center with such a positioning device that allow great accuracy and flexibility in view of positioning in a largest possible processing space, while allowing, at the same time, a simple, compact and cost-effective, but stiff, construction. In particular, stiff, stable and precise guiding is to be provided, wherein the footprint is reduced, as possible, and the moved dimensions are small, as possible.